White aqueous ballpoint pens comprising white pigments of high opacity, such as, titanium oxide, have been hitherto well-known. It is said that, when adopted to write on black paper or photographs, those ball-point pens are desired to have such high opacity that the color of the underlying paper or photographs can be concealed enough to make it easy to visually recognize the handwriting written thereon.
Meanwhile, in contrast with the white aqueous ballpoint pens, pastel-color ballpoint pens, as it is called, are also often adopted. They comprise white pigments incorporated with other colorants. When used in image processing of photographs and the like, they can make particular impressions. Because of that, pastel-color ballpoint pens are preferably employed.
Handwriting in colors other than white can be written with pastel-color ballpoint pens, which are hence usable for producing visually recognizable handwriting on white paper and the like. This means that they cover a wider range of use than white ballpoint pens. Accordingly, they are wanted to have various kinds of colors. If new color ballpoint pens are developed, they create new uses. As one of the uses, marker pens are known. Marker pens are writing implements with which, for example, particular words or letters printed or written on while paper are underlined or overpainted in colors so as to emphasis them. When writing implements are adopted as marker pens, they are required to produce transparent handwriting. Specifically, handwriting written with marker pens must be transparent enough to visually recognize the underlying handwriting overpainted with the marker pens.
In view of the above, it is desired to provide an ink composition having both opacity and transparency, which are two conflicting characteristics.